Oil well completions may employ electric submersible pumps (ESP's) to inject fluid from a source zone to a target zone. In some applications, such as artificial lift applications, the target zone is above the source zone and the ESP is configured to pump production fluid upward. In other applications, such as dump flood applications, the target zone may be located downhole from the source zone and the ESP is configured to pump injection fluid downward.
ESP applications in which the target zone is located downhole from the source zone may require very long tubing strings to convey the fluid from the ESP to the downhole target zone. Moreover, such applications may also require high fluid flow rates and thus relatively large tubing diameters. These requirements mean that the downhole tubing configurations can have very high weights and thus exert very high forces on structures that support the tubing. Thus, a challenging problem associated with such ESP applications is to provide safe and dependable support for the downstream tubing while meeting other operational requirements in a given well completion.
One known approach to address the aforementioned problem is to utilize a conventional ESP, oriented to discharge fluid upward, and a Y-tool or bypass system at the ESP discharge to reverse fluid flow. The flow is conveyed from the ESP discharge through the Y-tool and in a downhole direction to tailpipe tubing. While such solutions do address the problem of tensile capacity and supporting the heavy weight of the downstream tubing, they still have drawbacks. One drawback is that the bypass system or Y-tool may have limited tensile strength and therefore limited ability to support the weight of the downhole tubing to which it is connected. Another drawback is that conventional bypass systems or Y-tools are impractical for high flow rate applications since the bypass tubing and ESP must be positioned side-by-side within the wellbore, and thus the diameter and flow rate of the bypass system are necessarily limited.
Other solutions for ESP applications in which the target zone is below or downhole from the source zone may employ an ESP configured for bottom discharge, as is described, for example, in SPE142526 or in the document at http://www.slb.com/resources/technical_papers/artificial_lift/142526.aspx. Bottom discharge ESP's have the advantage of eliminating the need for flow reversal systems, such as Y-tools. However, support of the downstream tubing strings using the ESP structure is not practical because the ESP system is typically not designed with such support in mind and generally has poor tensile capacity.
Recently, pod systems have been recognized as providing advantages in ESP applications. Such pod systems are described in the above-referenced provisional application (FIG. 1) and in U.S. Pat. No. 8,448,699, assigned to Schlumberger Technology Corporation, the subject matter of which is incorporated herein by reference in its entirety.